1. Field
The present invention relates to micro devices. More particularly, embodiments of the present invention relate to a micro device transfer head and a method of transferring an array of micro devices to a different substrate.
2. Background Information
Integration and packaging issues are one of the main obstacles for the commercialization of micro devices such as integration of radio frequency (RF) microelectromechanical systems (MEMS) microswitches, light-emitting diode (LED) integration onto image display systems, and MEMS or quartz-based oscillators.
Traditional technologies for transferring of devices include transfer by wafer bonding from a transfer wafer to a receiving wafer. One such implementation is “direct printing” involving one bonding step of an array of devices from a transfer wafer to a receiving wafer, followed by removal of the transfer wafer. Another such implementation is “transfer printing” involving two bonding/debonding steps. In transfer printing a transfer wafer may pick up an array of devices from a donor wafer, and then bond the array of devices to a receiving wafer, followed by removal of the transfer wafer.
Some printing process variations have been developed where a device can be selectively bonded and debonded during the transfer process. Still, in both traditional and variations of the direct printing and transfer printing technologies, the transfer wafer must be debonded from a device after bonding the device to the receiving wafer. In addition, the entire transfer wafer with the array of devices is involved in the transfer process.